Viagra 100 mg relaxes muscles found in the walls of blood vessels and increases blood flow to particular body areas. Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which treats pulmonary arterial hypertension and improves exercise capacity in men and women. This page contains specific information for Viagra, not Revatio.Do not take Viagra while also taking Revatio, unless your doctor tells you to.